Where Is My Stopcock? How to Find and Use Your Main Water Shut-Off

What is a stopcock?

The stopcock is the main shut-off valve that controls the water supply into your property. Turning it off stops all water flowing into the house. In a plumbing emergency - a burst pipe, a major leak, or a failed fitting - the stopcock is the first thing you should reach for.

Where to find it

In most UK homes, the internal stopcock is under the kitchen sink, usually on the left-hand side where the mains water pipe enters the building. In older properties, it might be in a downstairs toilet, utility room, or under the stairs. In flats, check the airing cupboard or near the front door.

How to use it

Turn the stopcock clockwise to shut off the water and anticlockwise to turn it back on. If it has not been turned for a long time, it may be stiff. Do not force it with a wrench as you could damage the valve. Gently work it back and forth until it loosens. If it is completely seized, call a plumber.

Test it before you need it

Turn your stopcock off and on once or twice a year to make sure it moves freely. Turn on a tap to confirm the water stops when the stopcock is closed. It takes 30 seconds and could save you from serious water damage when it matters.

External stopcock

There is also an external stopcock in the pavement or front garden, usually under a small metal or plastic cover marked ‘W’ or ‘Water’. This belongs to the water company and requires a special key to operate. It shuts off the supply before it enters your property. Know where both are - if the internal one fails, the external one is your backup.